At present, the LED products are widely used in daily life. The LED (light emitting diode) has been gradually replacing the traditional halogen lamp as it has a stable property, is easily manufactured with a low cost and has the advantage of low power consumption. However, in a situation where a high light brightness and efficiency are required, e.g. in surgery, an illuminating apparatus quite matched with the application field is demanded for obtaining the effect of a lamp with uniform and shadowless illumination. Thus, a halogen bulb is still used. In view of the disadvantages such as high power consumption of the halogen bulb, the customer desires to obtain a solution capable of replacing the halogen bulb with the LED.